BALTIMORE â€” Adolescents living below the poverty line are more likely to have a waist line above healthy limits, according to researchers here.

Action Points

Explain to patients who ask that this study suggests that older teens from poor families are at increased risk of being overweight.

Inform teens and parents that this study further supports previous findings that physical inactivity, drinking sweetened beverages, and skipping breakfast are linked to overweight among adolescents.

BALTIMORE, May 26 â€” Adolescents living below the poverty line are more likely to have a waist line above healthy limits, according to researchers here.

The prevalence of overweight in older teens from poor families was 50% higher than in their non-poor counterparts, regardless of race or sex, said Richard A. Miech, Ph.D., M.P.H., of Johns Hopkins.

The greater numbers of poor adolescents who don't exercise, drink a lot of sweetened beverages, and skip breakfast may help explain the finding, Dr. Miech and colleagues said in the May 24/31 issue of the Journal of the American Medical Association.

The study examined data from the U.S. National Health and Nutrition Examination Surveys (NHANES) going back three decades. More than 5,000 adolescents were included. Poverty was determined by the U.S. Census Bureau poverty threshold.

For 1999 to 2004, the rate of overweight among older teens (age 15 to 17) in poor families was 23.3%, compared with 14.4% of older teens in non-poor families (P

"The observed differences across older versus younger adolescents are consistent with the greater autonomy that comes with increasing age," the investigators said. "Adolescents ages 15 to 17 years versus those ages 12 to 14 years have more opportunities to purchase their own food and determine their own leisure time pursuits and also have more discretionary income with which to act on their preferences."

For example poor older teens were significantly less likely to be physically active than their non-poor counterparts (odds ratio=1.71; 95% confidence interval=1.12 to 2.62). But there was no significant difference among younger teens (OR=0.77; 95% CI=0.47 to 1.25).

Drinking sweetened beverages and skipping breakfast were also significantly associated with being overweight among all adolescents, regardless of age or poverty status (ORs not given; P

In 1999 to 2004, the percentage of calories consumed from sweet drinks was highest among older teens from poor families (15.4% versus 12.6% for non-poor families; P=.002). In addition, 45.6% of these teens reported skipping breakfast, compared with 29.4% of their non-poor counterparts, the study found (P=.02).

However, eating out and snacking between meals were not significantly associated with overweight for any age or income group, the researchers said.

Finally, the study found no weight differences between poor and non-poor teens in earlier NHANES data from the 1970s and 1980s. This finding indicates that "a widening disparity in overweight that disadvantages adolescents in poor families has emerged in the 15- to 17-year-old age group in recent years," the authors said.

"These results suggest that efforts to reduce health disparities in the United States require monitoring of population health, so that emergent disparities and their underlying causes can be detected and addressed at early stages of their development," they concluded.

The authors noted some limitations of the study:

The BMI-based definition for adolescent overweight is recommended by the CDC, but the best way to identify overweight and obesity in children is still a subject of debate.

Data from Hispanic adolescents could not be meaningfully analyzed due to differences in sampling strategies and in measurement of Hispanic ethnicity across the NHANES surveys.

The cross-sectional design and methods used for NHANES limit investigation to only broad, major risk factors for overweight.

Measurement of family socioeconomic status is limited to self reported family income, because the NHANES data lack consistent measures of other socioeconomic status components.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine